Helical spline grinding machine



May 13, 1952 J. l.. JEssuP 2,596,814

HELICAL SPLINE GRINDING MACHINE Filed Feb. 24, 1949 l5 Sheets-Sheet 1 ll 1 l i F l l I I L t\ m, 1 N l l l 1 l i 1 l #W77 il SEF l I z w q MV QOQO m l Q 1! #l y d 5 t L x H WH l N35 l A: f *m l H N i fl 2Q l Nk R Nw N INVENTOR. /Yef Jszz/v. BY

May 13, 1952 J. L. JEssUP HELICAI.. SPLINE GRINDING MACHINE 15Sheets-Sheet 2 Filed Feb. 24, 1949 May 13, 1952 J. L. JEssUP 2,596,814

HELICAL SPLINE GRINDING MACHINE Filed Feb. 24, 1949 l5 Sheets-Sheet 5INVENTOR.

BY EEL. Myw

J. JEssUP 2,596,814

HELICAL. SPLINE GRINDING MACHINE Filed Feb. 24, 1949 l5 Sheets-Sheet 4 5E W M 2, N/ MNw. ffm manu... wwn t im MNM. www WI WMON Wm m w ,www ,fMM.. @L N vMay 13, 1952 May 13, 1952 J. l.. JEssuP 2,596,814

HELICAL SPLINE GRINDING MACHINE Filed Feb. 24, 1949 15 sheets-sheet 5May 13, 1952 J. l.. JEssUP 2,596,814

HELICAL SPLINE GRINDING MACHINE Filed Feb. 24, 1949 15. SheeS-Slleel'l 6May 13, 1952 J. l.. JEssuP 2,596,814

HELICAL SPLINE GRINDING MACHINE Filed Feb. 24, 1949 15 Sheets-Sheet 7May 13, 1952 J. L.. JEssuP n 2,595,814 HELICAL sPLINE GRINDING MACHINEFiled Feb. 24, 1949 15 sheets-sheet s [I] vs May 13, 1952 J. 1 JEssuPHELICAL. SPLINE GRINDING MACHINE l5 Sheets-Sheet 9 Filed Feb. 24, 1949xwm,

May 13, 1952 J. L. JEssuP 2,596,814

HELICAL SPLINE GRINDING MACHINE Filed Feb. 24, 1949 15 Sheets-Sheet 10IN V EN TOR.

479 @.LE. BY

| Afew .3%9//4 vMaly 13, 1952 JESSUP 2,596,814

HELICAL SPLINE GRINDING MACHINE Filed Feb. 24, 1949 15 Sheets-Sheet 1l Il l Eli I N VEN TOR.

May 13, 1952 J. JEssUP HELICAL SPLINE GRINDING MACHINE 15 Sheets-Sheet12 Filed Feb. 24, 1949 INVENTOR. Jfea' @5yd/y.

May 13, 1952 J. JEssUP HELICAL SPLINE GRINDING MACHINE 15 Sheets-Sheet15 Filed Feb. 24, 1949 INVENTOR.

BY Mwzm- Am .MM

May 13, 1952 .1. L. JEssuP 2,596,814

HELICAL SPLINE GRINDING MACHINE Fued Feb. 24, 1949 15 sheets-sheet 14FTTJiV/VEKS May 13, 1952 1 JESSUP 42,596,814

HELICAL SPLINE GRINDING MACHINE Filed Feb. 24, 1949 l5 Sheets-Sheet l5 QJNVENTOR.

BMQA'Q/fm Patented May 13, 1952 Eo fsf-re regs er j "19 -('Jlaims. (Cl.51-95) l ,invention .re1ates. genernny .to .grinding machines-.andthelike, ,and v more particularly to faQ-,helical- :spline grinding'machine.

.flt -is-:anoo-j ecttof. 'this `invention tov provide ,agrinding-machined the aforementioned -type in which the lead vbar-.is.connected to and disposed belowa reciprocating worktable so that theoverall l'length A-,of the l:machine is materially reduced, as`.co'rxipa red to machines `wherein the lead .bar

is-disposed-:abovethe-work table, and --so' that '1 the lead-,barisiprotected against metalchips fromthe wor-k- Tpiece, Y or otherV foreignparticles which citen adheretov leadlhars disposed .above thewor-letame.

@It-,is aFfurther-objectof Qthisinventior to pro- 1 generate iinvolutehclicalfsplines von .a work zpiece.

- Its-is a-fsltill further object of this invention to prfwide'zinfa'fg-rinding-machine- .of the-aforemen- .'tioned iltypef la 1 Ldouille.-acting .hack-lash device ,which isfoperably-.connected AtoV themachine 4 lead :bar-isoixas to :remove backlash in the lead har, changeispeedggearingfandwor-k index head, Afor pbotlfridirections v-of -table`reoiprocation.

EIMS-:a still furtherlooject `of this `invention 'to f ,providein-fagrinding amachine of fthe`aforementioneditypefmeansforsynchronizing,the'recipro-:cation-off'rfthefmarketable `with the operation-ofthe'eaforementionedbacklash device, so that when`'-.tlie-table,reaclfiesffthe end-of each reciprocatingvstroke-fthednacklashy devicewillv` be operated :to atake .thel backlashout -of fthemachine -in ythe .prQper'- direction gprior to thereciprocation .f fthecwork-tablein theopposite direction.

nas alstiufrnnther @bientot ltnisiinvention' ktn provide, in agrinding'machine offtheafore'men- .tioned typefagrinding wheel spindlequill', which is-reciprocable -inf-twodire'c'tions on--ar'iti-f-i'iction.bearingsgandf-feed- .screws kfor feeding -the quill .in :both(directions,` -each o f which Yengages and meshes with-lso :as to'rfee'd'the quillrgrooved #anti-friction rollers Awhich .are connected withdzheifquill, =.wheeby -zto eliminate lorY at -l east .Ina-:terialflyfreduce friction ,arid-lza'clrlashV -i-nthe `.quill operatingmechanismsothatthe voperatiomand i' contrer nf the" reaingpf fine"Vgrinding when is enhanced vlto provide *,an'litiemely accurateandtudient' machine.

-It :is afstill frtherbbject-,fthis invention to provide an improvedhydraulic circuitY and ysystem -for .operating the :movable elements oflthe grinding machine.

It `is a still' further object of .this-.invention to provide a grindingmachine of' 'the aforementioned v.type which is efficient in operation,exrem'ely accurate in use, and'durable infcon'strucion.

These and other objects of this `invention will ,become Aapparent fromthe ,following detailddescription takenA in-conju'n'ction .withtheaccompam'ing drawings, inV which:

Figures 1 -A and 1-B,- when'placed endto end, ,are longitudinalsectional -views..f the vmachine of this invention, with parts lor'okenaway in eiffivaism.-

L.lighl-.zfisfan Venlarged fragmentary sectional .view-ofthe-structure"illustrated ,in` Fig. l-B, taken along -theflinel 2 2thereof.

-.Eig.3.-is ranfenlarged fragmentary View, .partly in sectionvandpar'tly inelevation, -of the strucvture illustrated in Eig. 1"-Bgltaken .along the lline 3T-3 thereof. EigQ 4 isgase-ctinal .View ofthe'structure illustrated in,1ig'.3, .taken 'along' the linedthereof,with parts .broken away` fr purposes .of clarity. Fig. 5 A isa'fragrnentary 'sectinal'viewof'fthe structilre illustratedin` Fig. '3,Vtaken alongV Mthe line theiei".v

Fig` 6 .iNs-asectional view of the structureillusvtraten@ Fig.:stnkenniong-the,lin s-ls thereof.

V.7 is'la sectional'view-of `the-"structure illus- Ivtrated .in Fig.=.6,takenalong the line .1-:1 thereof.

is a sectional view of the structure illustrated ln -Fig..6, 1tal enalong the line 8--8 thereof.

l'gig .-9-isan' enlarged v iew partly-in section vand fpartly in#elevation;v of` the f structure illustrated .-in--Eig'- 1-B ,-ftakenalong -theline 9-9- thereof,

with certain parts of the machine illustrated diagrammatically inelevation for purposes of clarity.

Fig. 10 is an enlarged sectional view of the structure illustrated inFig. 9, taken along the line Ill-I thereof.

Fig. 11 is an enlarged fragmentary sectional view of the structureillustrated in Fig. 9, taken along the line thereof.

Fig. 12 is an enlarged fragmentary elevational .f

view of the structure illustrated in Fig. 11, taken along the line |2|2thereof.

Fig. 13 is a fragmentary sectional View of the structure illustrated inFig. 11, taken along the line |3|3 thereof.

Fig. 14 is an enlarged fragmentary sectional view of the structureillustrated in Fig. 9, taken along the line |4|4 thereof.

Fig. l is an enlarged fragmentary sectional view of the structureillustrated in Fig. 1l, taken along the line |5|5 thereof.

Fig. 16 is a View partly in section and partly in elevation of thestructure illustrated in Fig. 15, taken along the line |6-I6 thereof.

Fig. 17 is an enlarged fragmentary sectional view of the structureillustrated in Fig. 9, taken Fig. 18 is an enlarged fragmentary sideelevational view of the structure illustrated in Fig. l-B, taken withinthe circle I8 thereon, with parts broken away in section for purposes ofclarity.

Fig. 19 is an enlarged sectional view of the structure illustrated inFig. l-A, taken along the line |9|9 thereof.

Fig. 20 is a sectional view of the structure illustrated in Fig. 19,taken along the line 20-20 thereof.

Fig. 21 is an enlarged sectional view of the structure illustrated inFig. l-B, taken along the line 2|-,-2I thereof.

Fig. 22is an enlarged sectional view of the structure illustrated inFig. 9, taken along the line 22-22 thereof.

Fig. 23 is a vertical section through the Work index head shown in Fig.1-A.

Fig. 24 is a fragmentary sectional view of the structure illustrated inFig. 23, taken along the line 24--24 thereof.

Fig.'25 is a diagrammatical view of the hydraulic circuit and operatingmechanism of the machine of this invention.

Referring now to the drawings, it will be seen that thergrinding machineof this invention includesl a base or supporting structure 21,V which isenclosed by a housing, including side walls 29. A reciprocable worktable 3| is slidably supported on the top of the base 21 in ways 33 and35. A vertical column 31, in which is housed the operating andsupporting mechanism forY a grinding wheel 38, extendsupwardly above thebase 21, rearwardly of the reciprocating work table 3|, and is supportedon Athe base in any suitable manner. A tail stock 39 for supporting oneend of a work piece 40, is adjustably mounted in an inverted T slot 42,on the reciprocable work table 3|, in a conventional manner, andincludes (Fig. 18) .a housing 4|, having an axially movable center 44. Ashaft 43 is journalled in the housing 4| and carries a worm 41 on ytheinner end thereof, which meshes with a rack 49, formed on the undersideof the center 4|. A hand wheel 48 is connected to the outer end of theshaft 43 for operating the latter, and the pointed end of the centerengages and supports one end'of the work piece 40, as shown in Figs. 1-Aand 1-B. A coolant pump 5| and tank 52 are mounted in the base 21 forsupplying coolant to the work piece during the grinding operation in aconventional manner, and a coolant drain trough 53 and passageways 54are provided in the base for returning used coolant to its reservoirtank.

A work indexing head 55 is rigidly mounted on the work table 3| adjacentone end thereof and in spaced relation to the tail stock 39. The workindexing head is described in detail in the applicants Patent No.2,528,753 relating to Improvements in Index Head for Rotary spindles,and includes generally a housing or base 51 having a sleeve 59journalled in the rear portion thereof (Figs. 23 and 24). A drive shaft6| is rotatably supported in the sleeve 59 and the rear end thereofprojects outwardly through one end of the housing for connection tosuitable gearing, as will be hereinafter described. A second sleeve 63is supported in the front portion of the housing, in coaxialrelationship with respect to the sleeve 59, and a spindle 65 isrotatably supported in the'sleeve 63 and has a center 61 detachablyconnected thereto. An indexing mechanism 68, which includes an 'indexingplate 69 and a plunger 10 carried on worm gear shaft 1I, is supported inthe housing 5'1 for indexing the spindle 65 relative to the drive shaft6|. 'Ihe spindle drive shaft BI, indexing mechanism 99 and spindle 65are inter-connected by means of differential gearing 12, so that thespindle 65 can be driven by the drive shaft 6| independently of theindexingmechanism and so that the spindle can be indexed relative to thedrive shaft ylil by the indexing mechanism 68, even while the spindle isbeing driven by the drive shaft. The spindle center 61 is adapted toengage the opposite end of the work piece 40 from that engaged by thetail stock center and a dog type clamp 13 is provided, in a conventionalmanner, for driving the work between the spindle and tailstock centers,as will be hereinafter described.

In order to reciprocate the work table 3 I, a hydraulic piston andcylinder unit 15 is provided, which includes a movable cylinder 11 and apair of stationary adjacent pistons 19 and 8|, which have outwardlyextending hollow piston rods 83 and 85, respectively, connected thereto.The rods 83 and 85 have openings 86 in the walls thereof, adjacent theirrespective pistons, for a reason which will appear. The outer ends ofthe piston rods 83 and 85 are threadably connected in blocklike plates81, which -in turn are supported in vertical ribs Yor bulkheads 89 ofthe base 21. Fluid conduits 9| and 93 are threadably connected to theblock-like plates 81 so as to communicate with the outer ends of thepiston rods 8| and 83 respectively. The conduits 9| and 93 are connectedto a work table reversing valve 95, in a manner which will behereinafter described. A hydraulic iiuid reservoir or tank 99 is builtinto the bottom of the base 21 and a hydraulic pump |0| is supportedabove the tank 99 and has a suitable intake pipe or conduit 03 extendinginto the tank.

The right hand end of the cylinder 15, as viewed in Fig. l-B, extendsthrough an angle bracket |05 and has an annular shoulder |99 on the endthereof, which is connected to the vertical leg of the bracket |85, byany suitable means. The upper horizontal portion of the bracket |05 isconnected to the under side of the reciprocating work table 3| bysuitable means such as key |1 and cap screws |01; 'The piston'rodextends outwardly throughasuitable -s'e'al"-an'd'end"cap in thecylinder, 'for cor'n'iez'ztion nto" the 'plateiSI "The opposite fend fLthe "cylin- "der I 5 44is s'lidably "supported in fthe Vertical `por-`vti'o'nv of an angle"bracket I I I., 'Which is` similar fto thebracketr`Hl 5; 'and the "piston rodvll 8% extends 'outwardly' through' afsuitable's'eal v'l I3 v-andiend cap I I5 `in the" cylinder end'for-c'onnexcticn to lits plate 81. The upper horizontal-portion of theangle' bracket' II I `"is A'connected to the -under-side IVof therecipro'oable-work "table 31 A"by any suit able m'eans' such as "capl'screws AIii-'I and a` key 'I'I`I. v"I'herefore, when -hydra'ulicfluid-fis Iforced vunder pressure into, for example," 'the piston Arodlfiigitovvs through the rod 135 and into 'the-cylinder through the"opening""8-5; adjacentlitsinner `end,Wliile"^any *fluid'iin' theopposite-'endof the cylinder '15 flows .out "or" :the cylinder through`the `vopeningt adjacentlthe"innerl'endof the -piston rod83,'through'the piston rodi-'Baandback 'to the"control'valve-"$5=through ithe conduit "S, thenceto thepil reservoirg. Theinduction Aof'pressurizedliquidiinto'onepiston 'rod'or theA other causes the movementof lthe cylinder' =in lone vcli- "rec'tion' or'the "'oth'en and vwhen ithe vcylinder `and"`work' tablehave reached oneend Yof' `'their stroke;rtheir direction -ofr'n'ovemen't uis' reversed, in amanner whichvvillbe' here'ina'fter described., so that'reciprocationof the'^wo1l "table4is 'obtained. Thus, "by "hydraulically 4operating' the cylinder ''thework'table is recipro'cated and "the Work piece:ltlj'the'y indexingheadset `and 'tailstoclos'g are moved'ba'ck and "forth lacross the "baseIn order'to` control theileng'th of Athe'reciprocating strokes" of the'Work' table-3Iyafrack |23 is mounted lonlthe front 'Taceof` the Workltable and has 'a .pair Yofstop 'members' 1'25 movably positionedthereon. l'The stops 125 carry pau/ls I2'| which `are 'adapted ltoengage 'the rack 'teeth in any"predeterminedposition. The stops '|25'also Acarry 'dogsiI'ZB thereon-'f and ythe lposition 'of the dogs canYbe "adjusted by lmeans oiadjusting 'screws ISI. lThe dogsIZQ-arevadapted to engage a'lever 'element I'33 on the `reversingvalve-S5 'so -as' to causeV ashifting of the mechanism Vin *the* valve'Whichywill in turn vreverse the' `-iow "of 'hydraulic uid from onepiston rod 83 -or #to the other, in-amanner which AWilljbe herein-"after described. UAn''additionalfstopv 1131 is -carried `on the rackYI-23 -and 4is-fadaptedto 'engage the upperend -ofla'lever or 'fngerImember its, -which-isconnected to a shaftcIHv I(Figl 2'). The I'shaft11H-is rotatably supported in-the basegand has a depending nger forlever -I4-3Jconnected 'to the-'opposite Yend thereof. 'Thefinger-for'flever I 43 vis :adapted to engage la :plunger i fl rof the-valve 95, so as-tostop lthe moveinentoi thework Itable-'When itis-moving -frcm left to right as fviewediin Fig. 18.'This.arrangementpermits the tablefwhenlit has va'grindingWheel dresser-.there- Aon, to be fmoved to a `predetermined position, beyond the endAofthe reciprocating stroke, so as to bring the dresser Yup. to Lthe.wheel. I This Scan 'be accomplished by manuallyraisingfdog =l2i sothat'the'table Willlnotreverse,!but will bestopped fwhen the stop I`3'I`engages thelleverelement'ls.

vAfter the dressing operation .ithesreciprocation can 'again belstartedlrlziyactuating .the valve manuali-control handle M6 and vother.mecha- 'ni-sms. vas vvill be *hereinafterl described.

' As -the grinding "machine of this :invention vis primarilydesigned-'to grind helical splinesvitfis V-pro`i`1ided-with means forrotating `the spindle in synchronism with jthe reciprocations of theworke Atable. The preferred- Inechanismf `for this pur- 'pose is a helical:lead-bar elementfand acooperatting nut-j-element, either loneofmwhichirnay ibe mounted on the base of* the "machine-andthe otherrotatably journalled on the table-endop- Ieratively connected -to vtheAindexing `head spindle.

Work table 3i. Theright lhand end of the -lead `barlll'l, AasIbesti`seenin^Fig."leB, `is rotatably 'supported intheangle member' "m5by meansof bearings* II and Abearing supporting means 'The opposite-endV'of' the lead 'bar =I @il -is rotatably supported'in the anglememberill Vby means 'of bearings' 157, andprojects therethrough, vrseVas to oarrya gear I S'on the-extreme end thereo'f; 'beyondtheanglewrneniber Hl. The leadbar I'l'there'fore recipro'eates with `thecylinder Ve i and 'the work tableSI. In'order tri-impart 'rota- 'andthrust bearings T83.

tion to the leadbar vduring itsreciprocatioir'a pair "oflongitudinallyspaced -nutstl -and itil are' "provided, which engage 'the"leadbar 'fi and are rigidly connectedV to the 'opposite 'ends "or vanannular 'sleeve "''by means'oic cap 'screws (Figi 5'). Theisleeve'ldhasargear lformed on one 'endthere'o' and "thegear `Iiuneshes vWith theteeth of a rack' Ill, which `isl settued 'to a rnernb'c-:r H5; forreasons which will hereinafterappear. The sleeve M33is'rotatably'supportedinahousing I'Iby means oranti-friction bearings Ii9. The sleeve is secured against long'itudinalmovementin the housingI'IS by 'means 'of the gear portion JIE5? of the s1'eeve,'a"nut 81Therefore, While" 'the lead bar nuts |59 and 161 "are rotatable andadljustable 'for 'certain purposes, 'as"wi1l behereinafter 'brought'out, they are stationaryY during the longitudinal 'movement' of theVlead bar and 'thereby' impartrota'tion .to 'the lead bar vduring l 'itsmovement.

"Theleft hand end of theieadbar es?, asvievve in lFig.' l-A, 'isconnectedV to' the Work Aindexing "head drive shaft and'i'o't'atingspindle 6l 'and 65,

"[91.' 'Gears vIS'I and I9? are rotatably connected t9 an adjustable armor .bracket Issey suitable internally disposed bearings. The arm orbracket ISB isjjournalled at its lowerend on a hub member IBD, vvhi'ohis secured to the angle member Hl,

and'is adjustably connected to a vertical end Wall I9 I" o'fthe Worktable 3l by means of a cap screw H33," which extends through'anelongated 'slet I 95111 the arm. This assembly forms a reversingdevice"whih`may`be used to loharnge the hand of apait'being'ground, thatis,` to produce a' right or 'left"hand-helixv as desired regardle's tot`the number"of"gears in the change gear system or the hand'of the masterlead bar. 'It shouldbe noted thatthe gearslld |81 and |91 all have 1/1and thus does not enter into the calculations of the change gearing toproduce a desired lead on the part being produced. By loosening capscrew |93, the arm |89 can be pivoted to permit meshing either gear |81or |91 with the interchangeable gearing represented by gears |99, 20|,203, and other gears to be hereinafter described. One of an infinitevariety of gearing is represented in Fig. 19, in which gear |99 mesheswith the small gear 20| of a gear cluster 203, and the large gear 205 ofthe cluster meshes with the small gear 201 of a gear cluster 209. Thelarge gear 2|| of the cluster 209 meshes with a gear 2|3, which iscarried on the end of the indexing head drive shaft 6|. The gearclusters 203 and 209 are journalled on a fan shaped supporting bracketor arm 2 I9, and the arm or bracket 2 9 is pivotally supported on thedrive shaft supporting hub portion 22| of indexing head housing. Themounting shafts or bolts 2 I4 for the gear clusters 203 and 209 extendthrough elongated slots 2|5 and 2|1 respectively in the bracket 2|9, sothat various sized gears may be-employed when de. sired. The arm orbracket 2|9 is provided With additional slots so that the size andnumber of the change speed gears can be changed. It will thus be seenthat the lead bar is connected to .the drive shaft and rotating spindleof the informed on a work piece through a variance of the change speedgearing arrangement.

In order to protect the lead bar and the other operating mechanisms ofthe machine, which are disposed beneath the work table from dust, dirt,chips, or other foreign particles, a canvas strip 225 is provided. Oneend of the strip 225 is connected to a sheet metal housing 221 which isdisposed over the change speed gearing |85 and extends outwardly andover a roller 228 which is supported on the base adjacent one endthereof by means of a bracket 229. The opposite end of the canvas stripis wound around a drum 23| which is supported on the bracket 229 by apair of narrow canvas belts 233. The drum 23| is composed of a shaft232, an outer AShell and two end plates. plates far enough to allow thecanvas straps 233 to be attached to it. If the canvas strip 225 isrolled up on the large diameter of the drum before the canvas straps areattached to the l central shaft 232, the entire drum can be supported bythe two canvas straps. When the table moves to the right (as shown inFig. l-A) the canvas strip will be unrolled from drum 23| and in sodoing will cause the canvas straps 233 to be rolled up on the shaft 232.As the table moves to the left the weight of the drum will cause it tounroll the canvas straps from around the shaft and reroll the canvasstrip on the drum.

Thus the strip is always under a tension propor- Shaft 232 etxendsbeyond the end tend to cause wear or damage thereto. Likewise, it willbe appreciated that as the lead bar is disposed beneath the Work table,rather than above the base and longitudinally outwardly of the worktable, as in most conventional machines, the length of the machine ismaterially reduced and is approximately forty percent shorter thanmachines which have the lead bar mounted above the base, and on the worktable.

In the event that there is any leakage of the hydraulic fluid from thereciprocating cylinders 'l5 or any drippage from the lead bar |41, thebase is provided with a Ipair of longitudinally spaced andlongitudinally extending, inwardly and downwardly inclined plates 231and 239, which direct such fluid into a trap or sump 24|, whichsurrounds and is adjacent to the reservoir tank 99. The side Walls 29 ofthe base are provided with plugged apertures 243 at the bottom thereof,adjacent to the sump or trap 24| so that any sediment in the leaked uidcan be easily removed. In the event that there is a considerable amountof leakage in the hydraulic system, there is no danger of the fluidoverowing and spilling onto the floor, due to the fact that when thelevel of the liquid in the sump or trap rises to the level of the top ofthe reservoir tank 99, it will flow into the reservoir tank and will berecirculated through the hydraulic system. Any sediment in the leakedfluid Will have had a chance to settle to the bottom of the sump 0r trapbefore the fluid overflows into the tank. In this way a neat andeflicient manner of handling any fluid which may leak is provided,without the danger of any foreign particles or sediment getting backinto the hydraulic system.

One of the most prevalent diilculties in grinding machines has been thatof inaccuracies due to backlash which is set up in the lead bar, thework indexing head and the connections therebetween. It will beappreciated that with the machine of this invention, due to the changespeed gearing connection between the lead bar and the spindle of theindexing head, a great amount of backlash would ordinarily be present.

rIhis machine is therefore provided with a double acting backlash device245, which removes all of the backlash between the lead bar nuts and therotating spindle 55 of the work indexing head. This machine is,therefore, extremely accurate and the work piece will be properlyindexed, by an exact predetermined amount, during the reciprocation ofthe work table. This machine thus grinds work pieces much moreaccurately than has been lheretofore possible.

The double acting backlash device 245 is shown in detail in Figs. V3through 8, and comprises a housing 241, which includes a cylinder 249,having polygonally shaped members 25| sleeved on and vwelded to eachendthereof. End caps 253 are connected to each end of the housing 241,by means of cap screws 255, which extend through and are threadablyconnected to the sleeved members 25|. The housing 241 is connected to aslide 251 by means of cap screws 259. The slide 251 is slidably mountedin a dovetail way 26| of a plate member 263. The plate member 263 inturn is connected to a slide 265 by means of Vcap screws 261, and theslide 265 is slidably mounted in a dovetail way 269 in a plate member21| forming a part of the base of the machine. The slides 251 and 255may move relative to each other for purposes which will hereinafterappear. The slide 251 is a part of the rack supporting member |15, whichis connected to the rack |1|.

messia In. this way when the housing# 4.1 and ,the Slide.

25.11 move.. the rack |1|` will likewise.be..move.d so-.as to. rotatethe gear|61 formedon theend of, the .sleeve member |63,.which inturnw-ill. lio:y

tate.the .lead bar nuts. |59 and l-GI.. in 0r.der.. to eliminatebacklash, as will ,hereinafter appear.`

DisposedI within the. cylinder 2.49,. are.. a.. pair, ofV end toendpiston rods. 2].5wand 2.1.1. Theinnll end ofthe piston rod'. 2.15,'formed wth .a threaded .end portion 2.1.9 which iits.intlc` .v a.A

threaded. aperture'28| inthe.. innerendj ofthe.

rod 2.1.1.y and thev two rods .are immovably .cnnnected together. in anendV to. end.relationship,by`

meansoi taper pin 283-, sothatin effectasingle.

pistonrodis provided.. The. adjacent. inner .ends

offtherods 215 and 2,11. are externallyllhreadedtontothe threaded.portion 28,1",of1the rodjy 2111.'

The pistons 29| and 293 arel bore ttingpistons within the.cylinder 249andare provided with* a.. plurality. of .pistonrings or seals, 39|', inva conventimial manner.

The piston. rods 2 15 .and 211.'extend outwardlythrough their respectivepistons and through bores 3.93' which are. provided' in inwardlyextending, shank portions. 335 Aofi ,the end caps I253; as well vasthrough seals3.01""and' seal' retainers 309, which are carried intheouter ends ofi-the` end caps 253. 'I'he inner ends vof theshank'pgntions 305 of the endcaps253extendf inwardly.

through apertures 309'v in .the rear-or outer-wall'- ofthe pistons 29|Yand 293,- so 'that` the-cylinder- 249 and shank portions. 30.5 vare freeto slide 1011- gitudinally. with respectto the pistons-f The .outerperiphery of each .end cap Hshank 305-is formedj with a pluralityA ofcircumferentially spaced spline spaces 3|'01for-:a reason-thatwillvvhereinafter appear, and the wall ,of-` each .piston which denes`apertures 309' 'has apair- -of'opposed splines 3`|2 whichslidably*engagea pair-of' the spline spaces 310 for retaining lthepistons against rotation, but permitting-relative -axialj movement`between the end vcaps v and pistons.- Themovement of the cylinderrelative to the pistons 29| and .293- is lmitedfbytheshank portions- 305ofthe end-caps. For eXample-when-t-he cylinder moves to the left; theextent-,ofits movement is limited by the yengagement of the shoulder ofthe piston 293, adjacentthe threadedaperture 291,1 with the shankportion-305 of the end cap-253. The same piston -andshank abutment willoccur when the pistons moveto the rightand the piston 29| will engagethe adjacent shank portion 305.v

The outer end of the piston rod- 211,-outward-ly of the housing- 241, isjournalledl in an aperture 3|`|, in-a rib or plate 3|3 of the base (Fig.3)-, and aknurled handle or knob -3-|-5 is--secured to the outer end of;the rod for turning-the same.V The outerend of, the rod ,215extends-,outwardly -beyond the opposite vend of the housing 241,and isrotatably supported in a` journal block or bracket 3 1. The block 3 |1,in turn, is supported on, and rigidly connected to,` the plate 263bymeans yoi capscrews 3|9. The plate 263 is, of course, ind turnrigidlyconnected to the second slide 255.

valve 95 or to the tank side thereof, in accordance is. held. againstaxial, movement with respect thereto bamcans. `of; collar members 32|and nutsv 32.3... Therefore, whenthe knurled handle 3|5, ontheendof.the. r.0d 21.1, isrotated, pistons 2 9 I and 293 will" be rotated andwill` move axiallywithin., the cylinder 249.. As the threaded por--tions on the. inner ends ofthe. piston rods-are ofthe opposite hand, thepistonswi-llx be eithermovedtaward or away from each other-so that the.extentof relativemovement between the cylinder and pistonscan beadjustably controlled;

The..backlash.device is. connected in` the hydraulicsystemoithemachinein a manner which; willbehereinafter described, so that it will operateonly at. the endofeach reciprocating stroke ofthe table. Avhydraulicpassageway head-or block 325.. isattached von, one end of the cylinder249eanda similar block 325" is secured to the opposite endof thecylinder 249. The |block 325 andcylinder end member 25| are providedwith` afluid passageway 321-, which. has va conduitV 329` connected tothe outer endfthereof', and whichcommunicates .at its inner. endrwith'an.aperture 33|. in the wallolicylinder 249. The conduit- 329- is Yconnectedto .either .the pressure side `,ofy the with the positioningofcertain yalve means which will be hereinafterk described.. The wallaperture 33|. is .disposed .adjacent to but forwardly ofthe rearportion. of-lthe endjcap shank` 39.5 so 4that when. the, piston293 movesrearwardly or -outwardly, thatistoward the left` as viewed in Fig.V 6;-theaperture 33| will be closedv by the. piston. outwardlyv or.rearwardly of the passageway 321-,

` thel block, 325 and. .cylinder endmember. .25 v.are

provided with a. passageway .333," which extends parallel toy the.passageway 321 andwhich khas its4 outer end .normally closedby acheckvalve which includes a ball 335 and a spring 331, anditsinnerend-communicating with, an aperture 338i in the wall otcylinden 2.4.9..The free end of the spring 331 extends through. the cylinder wallandaouts a-portion ofthe .ends cap 253, outwardly or rearwardlyofthepshankportion 305.l The. passageway 32-1v isV connected. with the.passageway 333,

' outwardly-ofenbeyondthe .bal1.33.5,'by means of apassageway 339.` Thepassageways 321 and.333 are connected.l inwardlyof thecheckvalve bymeans ofy a passageway 34|, which communicates with and-extends at rightangles tothe passageway.v 321, a passageway 343- which communicateswithand extends at right anglesto passageway 333, and a passageway 345.which connects pas.- sageways 34| and 343..

A-meteringpin 341l is` threadably connectedn to the block 325:andsecuredby-a lock .nut 349. The

The outer endv of the pistonrod2'|5, while being inner endof the-.pinextendsinto the passageway 34-5.- The outer end of the pin 341 isprovided with -a k-nu-rled handle-.350 to-permit the pin to .be threadedinto 01' outA of the block-3325 so as..to. adjust -thef--posi-tionof-theinner end-of the pin` in the passageway-,345and-therebycontrol-the flow ofv i-ud, through the passageway 345. Theblock 325' onfthe opposite end of the cylinder ,is constructed inthe`same manner as the vblock 3.25 previously descrbcdand correspondingparts of the lblock 32 5f: are` indicated by primednumbers.corresponding to thenumbers employed ,in connectionwith the descriptionofthe block 325.

Invoperation, when it isdesired to actuate the backlash device, theApiston rod 'handle 3 I5 isA turned so as topoosition the pistons 29| and293V ina desiredrelatipnship withrespect to the cylinder anlgthe"shankportion 395 ofA the cylinder end caps;- that ie,- the pistonsare positioned 'so that

